The present invention relates to quick-connect fasteners and, more particularly, to ¼ turn fasteners which can be fastened and unfastened quickly and repeatedly.
As can be seen from Prior Art FIG. 1, fasteners 10 of the ¼ turn type have been known which include a grommet 12 and a stud 14 mounted on a first panel and a receptacle 16 mounted on a second panel. The fastener 10 holds together the two panels 18 and 20, with adjacent sides of the panels in contact with one another, by extending through openings 22 and 24 formed in the panels to receive the fastener. The grommet 12 has a cylindrical body 26 sized to extend through the opening 22 in the first panel 18, usually an outer panel, and one end of the cylindrical body 26 has a radially outward extending flange 28 to engage the outer surface of the first panel 18. The stud 14 has a shaft 30 and a head 32, and is part of a fastener assembly with the grommet 12, a cross pin 34 extending through the shaft at an end opposite to the head, a cup member 36 slidable along the shaft, and a spring on the shaft between the head and cup member and received in the cup member. The stud 14 is received in the grommet 12, with the head 32 of the stud being adjacent to the flange 28 on the grommet and a radially outward extending flange 38 on the cup member 36 engaging a radially inward extending flange 40 at the end of the grommet 12 opposite to the radially outward extending flange 28. This arrangement keeps the head 32 of the stud 14 biased by the spring slightly outward from the radially outward extending flange 28 at the outer side of the first panel 18. The cross pin 34 on the stud 14 prevents the assembly of the grommet 12 and the stud 14 from separating from the first panel 18.
The receptacle 16 of the fastener 10 has a generally cylindrical body 42 and a flange 44 projecting radially outward from one end of the body. The receptacle body 42 defines a central opening and has cam and locking surfaces 46 defined at an end opposite the radially outward extending receptacle flange 44. The receptacle flange 44 is placed against and secured to a side of the second panel 20, usually an inner panel, opposite to the side contacting the first panel 18, with the receptacle body 42 extending away from the side of the second panel 20 to which the flange is attached. The panels 18 and 20 are brought together so that the stud 14 and the receptacle 16 are in alignment. The head 32 of the stud 14 is engaged by a turning tool, such as a screwdriver, pushed inwardly against the bias of the spring, and turned ¼ turn with the cross pin 34 of the stud in engagement with the cam and locking surfaces 46 of the receptacle 16. This action locks the fastener 10 in place with the two panels 18 and 20 in secure engagement with one another.
A drawback of such a fastener is that, when the fastener is in a released position, the cross pin 34 and a significant portion of the stud shaft 30 are free to extend beyond the cup member 36 and the grommet 12 toward the second panel 20. This extension of the stud 14 and the cross pin 34 interferes with proper positioning of the first panel 18 on the second panel 20, because the extending stud and cross pin “hang up” on any of various surfaces as the portion of the fastener 10 including the stud and cross pin is being aligned with the portion of the fastener including the receptacle 16. In a “hang up”, the extending stud 14 and cross pin 34 prevent proper alignment and securement of the fastener 10. In such a situation, the head 32 of the stud 14 must be pulled outward to reduce the inward extension of the stud 14 and cross pin 34, and thereby eliminate the interference of the stud and cross pin with the proper alignment of the two portions of the fastener 10. Typically, the first panel 18 is provided with a plurality of spaced fasteners 10. As a result, the placement of the first panel 18 relative to the second panel 20 becomes difficult as an installer tries to hold the first panel in position while trying to pull out the stud 14 on a plurality of fasteners 10 to eliminate interference caused by the inward extension of the studs 14 and cross pins 34. Placement of the first panel is especially difficult where the first panel 18 is a curved panel, such as an aircraft engine cowling panel.
One fastener created to ease this challenge is disclosed in U.S. Pat. No. 5,688,093 (the “'093 patent), which is incorporated herein by reference in its entirety. As can be seen in FIGS. 2 and 3, the '093 patent discloses a ¼ turn type of fastener 50 having a grommet 52, a stud 54, a receptacle 56, a cross pin 74, a cup member 76, and a locking spring 77. When the fastener 50 is released by turning the stud 54, an ejecting spring 90 expands, moving the cup member 76 upward and, with the cup member 76, moving the locking spring 77, the stud 54, and the cross pin 74 upward until the cross pin engages a bottom surface of the grommet 52. The biasing force of the locking spring 77 is greater than the biasing force of the ejecting spring 90. With the stud 54 ejected to this point, there is very little likelihood of the stud 54 or the cross pin 74 hanging up as the panel 58, with the outer portion of the fastener 50, is being aligned for engagement with the inner portion of the fastener. However, installing the stud 54 into the grommet 52 can be difficult with the ejecting spring 90 in between. Consequently, there remains room in the art for improvement.